As thousands turned out in Tel Aviv last weekend to protest against the bill to investigate the funding of left-wing, Israeli NGOs, several major American Jewish organisations voiced their opposition to the move.

They argue that the bill, which proposes setting up a parliamentary panel to look into NGOs that criticise the Israel Defence Forces, threatens the country's democratic values.

It is the most significant revolt since the Rotem Conversion Bill drew almost unanimous opposition from the American Jewish community last summer.

The Union for Reform Judaism said it was "deeply concerned" by the move to investigate NGOs which, it said, "undermines Israel's place in the global community".

The American Jewish Committee said the Knesset's action "contravenes the democratic principles that are Israel's greatest strength".

"Israel's vibrant democracy not only can survive criticism," said David Harris, the AJC's executive director, "but it also thrives and is improved by it."

Coming less than a year after Peter Beinart's explosive essay in the New York Review of Books - which castigated mainstream Jewish organisations for not speaking out against the erosion of democratic values in Israel - such strongly-worded criticism is notable.

But according to the organisations themselves, their opposition should come as no surprise.

The motion to establish the parliamentary inquiry was introduced by members of Yisrael Beiteinu, and Mr Harris has spoken out against the party's leader, Avigdor Lieberman, in the past.

And an AJC spokesman emphasised that Mr Harris's criticism of this latest bill did not signal a change in attitude towards Israel.

"This is not an expression of existential angst or doubts about Israel," he said. "We are simply saying this is not the most helpful measure and that it runs counter to the basic principles of Israeli democracy."

Such a response was echoed by Rabbi Elliott Kleinman, a senior member of the URJ, who said: "Whenever we feel Israel is acting to undermine its democratic values the Union is going to speak out."

The Anti-Defamation League, often quick to attack those who criticise Israel, also opposes the bill.

ADL national director, Abraham Foxman, said Israel does have genuine concerns about foreign governments, particularly European governments, funding organisations that challenge Israeli policy. Nevertheless, the bill, Mr Foxman said, is dangerous because it specifically targets groups of one political persuasion - those to the left of centre.

"We are opposed to any legislation that singles out left or right," Mr Foxman said.